If you use firefox you can change the orkut backgroung by using the greasemonkey firefox extension. First install greasemonkey from here and then install Bluekut hack from here

2. Orkut Cute
Orkut cute is a program that let you send scraps to all your friends in orkut. It also alerts you when you receive new scraps send notifications when forums are updated. Orkut cute can be downloaded here.

3. Sorkut Firefox Extension
This is a toolbar to search for the threads with specific words in the title. Just give the commumity id of the community you want to search, enter the search term and click Search.

4. Scraboy
This is a freeware program that let you browse orkut and know when you or your friends receive new scraps. You can add emoticons, colour and formatting to your scraps with ease. Sending scraps from your desktop is also as easy as writing an instant message. Scrapboy can be downloaded from here.

5. Orkut Scrap Helper
This is a cool firefox extension that let you scrap faster by providing messaging options in your own scrapbook page. It also reduces the number of steps to scrap someone who has scrapped you to just one!. Scrap helper can be downloaded from here.

6. Scrapbook Flooding
An Indian dude named Rahul created this Firefox extension for Orkut scrapbook flooding. The extension is compatible with Firefox1.5+ and can be downloaded from here.

7. Javascript Hacks
There are some Javascript hacks for Orkut. Like, for flooding scrapbook, Increasing number of fans, testimonial flooding, Invisible names, blank scraps, etc. Some of them do work.
A good compilation can be found here. Try at your own risk.